1. Field of the Invention
The subject of the invention is a method for determining the sampling phase for signals having digital modulation of n-PSK type and a method for detecting synchronization word implementing the method for determining the phase. The invention applies in particular within the context of a digital decoder in accordance with the Digital Video Broadcasting (DVB) with return channel specification.
2. Discussion of Background
To demodulate a signal modulated with the aid of a 2n-PSK type modulation (with constant envelope) and thus retrieve the symbols transmitted, it is necessary to sample the signal at the symbol frequency with a correct phase. The algorithm of Gardner makes it possible to determine the appropriate sampling instant. This algorithm has the drawback however of requiring a certain convergence time, during which time the symbols received are lost.
When the signal transmitted includes bursts, this convergence time may be prejudicial to the proper operation of the receiver. Specifically, a short burst may be of insufficient duration to obtain synchronization. Moreover, if the bursts are dispatched by different transmitters, it is not possible to maintain synchronization from one burst to another.